Furnace for reducing metallic oxids.



O. M. JOHNSON.

FURNACE FOR REDUCING METALLIC oxms. APPLIGATIONTILED FEBA, 1910.

Q64,871. Pa ented July 19, 1910.

2 SHEETS-SHEET 1.

FIGS.

FIG-1.

WITNESSES I c. JOHNSON. 'IUBNAGE TOR REDUCING METALLIC OXIDS.

APPLICATION FILED P1114, 1910.

.9 4 71 Patented July 19, W10.

2 EHI-ETS-SHEET 2.

. M 9 gm Q) QLQCL Qt QLMQ E UNITED STATES PATENT oni ion.

CHARLES MORRIS JOHNSON, OF AVALON,- PENNSYLVANIA, ASSIGNOR TO CRUCIBLESTEEL COMPANY OF AMERICA, OF PITTSBURG, PENNSYLVANIA, A. CORPORATION OFNEW JERSEY.

FURNACE FOR REDUCING METALLIC OXIDS.

Specification of Letters Patent.

Patented July 19, 1910.

Application filed February 4, 1910. .Serial No. 541,983.

"of the United States, have invented or discovered certain new anduseful Improvements in Furnaces for Reducing Metallic ,Oxids, of whichimprovements the following is a specification.

My invention relates to improvements in the construction of furnacesemployed in the reductiono'f metallic oxids, and the object of myimprovement is simplicity'of structure.

In the accompanying drawings, which form part ofmy specification, Figure1 illustrates my improved furnace in longitudinal vertical section; Fig.2 shows the same structure in longitudinal horizontal section, withslight inodifications, the furnace chamber itself being shown in plan;Fig. 3 is a view in perspective of a receptacle for the furnace charge;andFig. f is a view similar to Fig.

- 3, illustrating'a modification.

Referring to Fig. l of the drawings, the chamber itself is indicated atl. TlliS'CllillIlher is preferably of cylindrical form, of relativelygreat length as compared with its width, and may advantageously beformed of a section of iron pipe; and I mean by iron pipe either wroughtiron pipe' or steel pipe, for cast iron pipe is not adequate for thepurposes which I now contemplate, although it may be. useful for otherreducing operations involving my invention and yet requiring lesselevated temperatures. This cylindrical reduction chamber is preferablyarranged in horizontal position, and necessarily a substantial part ofit extends within the furnace walls 4. It is however a feature of mypresent invention to prolong this cylindrical, horizontally-disposedreduction chamber outside of thefurnace walls, and to provide a gas ventin the said prolonged part of the reduction cliambeiywvhich gas ventshall open to the atmosphere.

My invention further consists in the form of receptacle whicl Ipreferably employ for containing the furnace charge. This receptacle,which is indicated at 8, 8 of the draw-. ings, is of cylindrical formwith closed ends and open upon one side. This cylindrical receptaclewill preferably be of relatively great length as compared with itswidth, and the opening through its side will preferably extendperipherally less than half way around the cylinder. Braces 10 may beemployed intermediate the length of the receptacle and connectingopposite sides of the opening, to strengthen the receptacle againstdistortion under the hard conditions of service to which it issubjected. Such a cylindrical-receptacle corresponds in shape and insize to the cylindrical reduction chamber, being sufficiently smallerthan the said chamber to adinit of its being introduced into and removedfrom that chamber. It will preferably approximate the reduction chamberin transverse diameter, that it may fit snugly therein andoccupysubstantially all of the transversespace within thereduction'chamher, and its construction is such as to admit of its readyintroduction and witlulrawai. To'this end, 1 preferably employ theconstruction which is particularly illustrated in Figs. 3 and 4 of thedrawings, wherein it ap pears that the ends of the cylindricalreceptacle' are formed with inwardly turned flanges which in theassembling pass within the bore of the cylindrical body of thereceptacle, and when so located are riveted to the body of thereceptacle. The heads of the rivets will, it will be understood, behammered smooth, and will project as little as possible from theexternal surface of the receptacle. By this construction the size of thereceptacle may be brought to a maximum.

In Fig. 4 I have shown a slight modification in the construction of thisreceptacle, with the end in view of overcoming the danger of having thereceptacle, after being subjected to high heat while within. thechamber, adhere to the inner surface of the chamber wall. In the formshown in Fig. 3, this danger is to some extent guarded against by theheads of the rivet-s which secure the ends of the receptacle in place.These rivet heads, however fiat they may be hammered, project beyond thegeneral surface of the receptacle, and upon these rivet heads thereceptacle will normally rest when in place within the. chamber. Contactbeing thus concentrated at a few points of small extent, difficulty fromsticking is largelyovercome. But in Fig. t I have shown more effectivemeans. Such a receptacle is liable short intervals of time.

to some distortion under the conditions of its use; and, in the case ofthe receptacle shown in Fig. 3, a slight change in shape may bring largeportions of the external surface of the receptacle into contact with thechamber wall; furthermore, dust gathermg from the operatlon may collectand coat the outer surface of the receptacle and bridge the small spaceseparating that surface from the chamber wall, so causing obectionableadherence. In Fig. L I- show cleats or strips, 11 (the number andpositions of which may be varied), riveted to the receptacle on itsouter and under side. In this case, the heads of the rivets by whichthese cleats or strips are secured form thebearing points upon which thereceptacle rests within the chamber. The greater space thus providedbetween the outer surface of the receptacle and the chamber wall affordsbetter security against sticking either through distortion of thereceptacle itself or through the collection of dust referred to above;furthermore, in case the receptacle should stick in the bore of thefurnace, the space afforded by the cleats allows the insertion of aninstrument 'to pry the receptaclefree. It will be observed that in thiscase (Fig. 4t) the size and capacity of the receptacle are to someslight extent sacrificed, but

this is so small a matter as to be of no practical consequence.

My improved reducing furnace finds its particular application in thereduction of tungsten oxids and like substances after the method whichis described in an application for Letters Patent filed by me June 19,1909,

Serial No. 503,112..

My furnace, as I have here described it, is particularly advantageousfor the performance of the operation described in the applicationreferred to and for like operations in the following respects:

First: Tungsten oxids and like oXids, and such carbon-containingmaterials as are employed in their reduction, are relatively poorconductors of heat; and, if a reducing operation be performed on a bodyof such tending the mass of the furnace charge of this nature into arelatively attenuated body 'of small thickness, the necessary heatingand cooling which are incident to the reducing operation may beaccomplished in relatively My furnace,

formed as it preferably is of pipe sections, is designed to receive afurnace charge in such attenuated form.

' Second: By prolonging the reduction chamber through and outside of thefurnace walls, it is ready of access for charging and withdrawing thecharge; and, the gas vent being arranged at the extreme end of suchprotruding portion of .the reduction chamher, the furnace charge itself(whichliesin that part of the reduction chamber which extends inside thefurnace walls) is the more effectually guarded against the ingress ofair during the cooling operation, while the reduced charge at elevatedtemperature is liable to injury if reached by the atmosphere.Futhermore, by thus prolonging the chamber from the furnace wallexternally, a tight fit of the removable cups 2 and 3 may be maintained,which otherwise would be a matter of ditliculty.

Third: My furnace, constructedas I have described it, is not only formedof the simplest, cheapest and most easily obtained materials, but it isin its structure simpler than any other such furnace known to me forreducing tungsten oxids and like substances. It requires in itsoperation no flow of reducing gases from any outside source, and thefurnace chamber is a closed chamber, but to the single gas vent which Ihave described.

Fourth: The'employment of iron pipe for the reduction chamber is, so faras I am aware, new; and, as compared with other materials commonly.employed, is exceedingly cheap. It is possible to use iron for thispurpose because, while the temperature to which the walls are subjectedis such as would soon effect the destruction of the iron chamber wallsif the substances within t1 e chamber were of an oxidizing nature, sinle the gas within the chamber during the operation of reduction is areducing gas, the walls are not injured while the high heat ismaintained.

Fifth: The receptacles or boats, such as I have described for receivingthe furnace charge, may be formed of iron also, the cheapest materialavailable, and the boats formed of this material are not injured by thehigh temperatures involved; because, when so highly heated, thereceptacles are themselves protected against injury by being envelopedin a reducing gas.

As indicated in Fig. 2, the furnace there employed includes tworeduction chambers such as I have described, connected at one endthrough the connecting pi e 9. In the operation of such a double-chamberfurnace, the rent 6 of one of the two chambers may be plugged, and thevent (3 of the other left open. It may be convenient to place a valve inthe connection between the two chambers, so that either chamber may beused independently of the other.

operation appi'oaches completion, there will As is indicated in Fig. l,the reduction chamber 1 may be removable in $0250 from the furnacewalls, so that after the reduction has been accomplished the Whole maybe withdrawn to hasten the cooling.

The means of heating may be of any pre-- ferred character; and, as shownin Fig. 1, a gas burner 5 is illustrated for this, purpose.

I have noted above that it is not necessary to the operationof myimproved furnace to inject into the reduction chamber during theprogress of the operation a flow of reducing gas derived from someexternal source. Nevertheless, in order to guardagainst any injuriouseffects of leakage, I may as a precautionary meisure, introduce a supplyof reducing gas after the operation is performed and during the coolingof the furnace. To this end I have shown a supply pipe, 13, for such agas leading to thechamher; and my preferred use of this auxiliary gassupply is as follows, As the reducing be a drop in the flame of carbonmonoxid burning at vent 6. \Vhen this flame falls, I allow reducing gasto enter through pipe 13, and then I remove the source of reducing heat,as by turning off the burners In my original application before referredto I showed a single chimney for the furnace. I have found it desirableto have the furnace chamber 1 arranged adjacent to theupper wall of thefurnace, and I have found a single chimney in this upper wallobjectionable in causing the adjacent portions of the pipe 1 to burn outrapidly. Accord-l ingly, I have adopted a number of chimney ports distlibuted over the upper furnace wall adjacent to which the pipe furnacechamber 1 extends.

I claim herein as my invention:

1. In a reducing furnace the combination of a cylindrical furnacechamber extending within furnace walls and a receptacle for the furnacecharge, such receptacle being of incomplete cylindrical form, withclosed ends and open along one side of its cylimh'ical surface,substantially as described.

2. In combination with a cylindrical furnace chamber a receptacle forthe charge of a reducing furnace in the form of a cylinder with closedends and open on its cylindrical side to an extent less than half itsperimeter, substantially as described. 4

3. The combination-With the cylindrical chamber of a'reducing furnace ofa receptacle for the furnace charge consisting of a cylindrical bodyopen along its side and flanged ends riveted in place Within the bore ofthe cylindrical body, substantially as described. 4. The combinationwith the cylindrical chamber of a reducing furnace of a cylin dricalreceptacle for the furnace charge provided externally with supportingcleats, substantially as described.

In testimony whereof, I have hereunto set my hand.

CHARLES MORRIS JOHNSON.

- WVitnesses SUE i3. FRITZ, BAYARD H. CHRISTY.

